Bone indentation recovery time correlates with bond reforming time

Area of Science:

• Biomaterials Science
• Nanotechnology
• Orthopedics

Background:

• The molecular mechanisms underlying bone's toughness and strength are not fully understood.
• Bone's nanocomposite structure, primarily hydroxyapatite crystals and collagen, plays a role in its mechanical properties.
• Energy dissipation mechanisms in bone are crucial for preventing fracture but remain largely unknown.

Purpose of the Study:

• To investigate the molecular basis of bone's toughness and energy dissipation.
• To explore the role of the organic matrix, specifically collagen, in bone's mechanical resilience.
• To compare bone's toughness mechanisms to those of other biocomposites like abalone nacre.

Main Methods:

• Utilized atomic force microscopy (AFM) to probe bone's mechanical properties at the molecular level.
• Investigated the presence and behavior of polymers with sacrificial bonds in bone.
• Correlated the reformation time of sacrificial bonds with bone's toughness recovery using AFM indentation testing.

Main Results:

• Bone, similar to abalone nacre, contains polymers with sacrificial bonds.
• These sacrificial bonds protect polymer backbones and dissipate impact energy.
• The time for sacrificial bond reformation in bone correlates with its measured toughness recovery.

Conclusions:

• Sacrificial bonds within or between collagen molecules are likely key contributors to bone's remarkable toughness.
• Understanding these molecular mechanisms could lead to improved treatments for bone fragility and fractures.
• This study provides a molecular explanation for bone's ability to withstand mechanical stress.